PTEN and breast cancer: It has recently been shown that these hormonal, reproductive, metabolic, and environmental factors can induce epigenetic changes [55], such as hypermethylation of tumor suppressor gene promoters such as BRCA1 [56], CDH1, RASSF1A, and PTEN, or histone modifications (EZH2, HDAC1), which alter gene expression and modulate the effect of genetic variants related to breast cancer risk [57,58].